Full Duplex DOCSIS Node Using Complementary Transmission Groups
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Solution Overview
Problem
Conventional Hybrid Fiber Coaxial (HFC) plants face challenges in achieving full duplex operation due to the inability to create high-gain amplifiers that can amplify the same spectrum in both directions using analog components, leading to signal distortions, high complexity, and high costs, and require extensive fiber penetration to deploy full duplex nodes.
Innovation Solution
Deploying a Full Duplex (FDX) DOCSIS node in an N+x HFC cable plant using non-full duplex amplifiers with a control unit that assigns Cable Modems (CMs) to different Transmission Groups (TGs) with complementary Resource Block Assignments (RBAs), allowing amplifiers to support Frequency Division Duplex (FDD) split within the FDX band, enabling full duplex operations even in N+x cable plants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a Full Duplex Amplifier is designed to amplify the same spectrum in both directions using analog components, then high-gain amplification capability is improved, but device complexity and cost increase significantly due to required echo cancellation functionality
Solution Approach 1:
The patent replaces the mechanical/analog echo cancellation system with a digital signal processing approach. Instead of using complex analog components and circuits for echo cancellation in the amplifier, the system uses digital signal processing at the CMTS to cancel upstream signals from downstream signals in the digital domain. This substitution dramatically reduces the complexity of the amplifier hardware while maintaining full-duplex operation capability.
2Power
If a Full Duplex Amplifier is designed to amplify the same spectrum in both directions using analog components, then high-gain amplification capability is improved, but manufacturing cost increases due to high complexity requirements
Solution Approach 1:
The patent replaces the mechanical/analog echo cancellation system with a digital signal processing approach. Instead of using complex analog components and circuits for echo cancellation in the amplifier, the system uses digital signal processing at the CMTS to cancel upstream signals from downstream signals in the digital domain. This substitution dramatically reduces the complexity of the amplifier hardware while maintaining full-duplex operation capability.
3Reliability
If conventional HFC plants use FDD configuration with diplexer filters in amplifiers, then upstream and downstream signals are isolated effectively, but full duplex operation on the same frequency band cannot be achieved
Solution Approach 1:
The patent replaces the mechanical/analog echo cancellation system with a digital signal processing approach. Instead of using complex analog components and circuits for echo cancellation in the amplifier, the system uses digital signal processing at the CMTS to cancel upstream signals from downstream signals in the digital domain. This substitution dramatically reduces the complexity of the amplifier hardware while maintaining full-duplex operation capability.
Solution Approach 2:
The patent changes the operating parameters of the system by allowing upstream and downstream signals to occupy the same frequency spectrum simultaneously. Instead of using fixed frequency separation with diplexer filters, the system uses dynamic digital signal processing to separate the signals in the time domain through echo cancellation, enabling full-duplex operation on the same frequency band.
4Adaptability or versatility
If fiber penetration depth is increased to deploy full duplex nodes, then full duplex operation becomes possible, but infrastructure cost and complexity increase
Solution Approach 1:
The patent replaces the mechanical/analog echo cancellation system with a digital signal processing approach. Instead of using complex analog components and circuits for echo cancellation in the amplifier, the system uses digital signal processing at the CMTS to cancel upstream signals from downstream signals in the digital domain. This substitution dramatically reduces the complexity of the amplifier hardware while maintaining full-duplex operation capability.
Data Source
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AI summary
The present document discloses a method for deploying a Full Duplex, FDX node in a cable system using a FDX band divided into sub-bands. The cable system comprises a plurality of Cable Modems, CMs, coupled to a cable network, and an amplifier. The method comprises assigning a first number of CMs located on one side before the amplifier to a first transmission group and a second number of CMs located on another side after the amplifier to a second transmission group; and assigning a same first configuration set of transmission directions of the respective subbands in the FDX band to the CMs in the first transmission group and a same second configuration set of transmission directions of the respective subbands in the FDX band to the CMs in the second transmission group, wherein the transmission direction is either downstream or upstream. For a respective sub-band used by both transmission groups, the respective transmission direction of the respective subband in the first configuration set is assigned to be complementary to the respective transmission direction of the respective subband in the second configuration set.